Modelling radiation emission in the transition from the classical to the quantum regime

An emissivity formula is derived using the generalised Fermi-Weizacker-Williams method of virtual photons which accounts for the recoil the charged particle experiences as it emits radiation. It is found that through this derivation the formula obtained by Sokolov et al using QED perturbation theory is recovered. The corrected emissivity formula is applied to nonlinear Thomson scattering scenarios in the transition from the classical to the quantum regime, for small values of the nonlinear quantum parameter \chi. Good agreement is found between this method and a QED probabilistic approach for scenarios where both are valid. In addition, signatures of the quantum corrections are identified and explored.Comment: 11 pages, 4 figures, submitted for publicatio

Management of Iatrogenic Urorectal Fistulae in Men with Pelvic Cancer

INTRODUCTION: Urorectal fistula (URF) is a devastating complication of pelvic cancer treatments and a surgical challenge for the reconstructive surgeon. We report a series of male patients with URF resulting from pelvic cancer treatments, specifically prostate (PCa), bladder (BCa), and rectal cancer (RCa), and explore the differences and impact on outcomes between purely surgical and non-surgical treatment modalities. METHODS: Between October 2008 and June 2015, 15 male patients, aged 59-78 years (mean 67), with URF induced by pelvic cancer treatments were identified in our institutions. Patients with a history of diverticulitis, inflammatory bowel disease, or other benign conditions were excluded. We reviewed the patients' medical records for symptoms, diagnostic tests performed, type and etiology of the fistula, type of surgical reconstruction, followup, and outcomes. RESULTS: Fourteen patients underwent surgical reconstruction. One patient developed metastatic disease before URF repair and, therefore, was excluded from this study. Mean followup (FU) was 32.7 months (14-79). All patients received diverting colostomy and temporary urinary diversion. An exclusively transperineal approach was used in nine (64.3%) patients and a combined abdominoperineal in five (35.7%). Overall successful URF closure was achieved in 12 (85.7%) patients, nine (64.3%) of whom at the first reconstructive attempt, two (14.3%) after two attempts (in our institution), and one (7.1%) after three attempts (two of which elsewhere). An interposition flap was used in seven (50%) patients. Surgical reconstruction failed ultimately in two (14.3%) patients who still have a colostomy and do not wish any further reconstruction. CONCLUSIONS: Our study has several limitations, including its retrospective nature and the heterogeneity of our small patient cohort. Nonetheless, although surgical reconstruction of URF may be extremely difficult and complex in the non-surgical/energy ablation patients, its successful reconstruction is possible in most through a transperineal, or a more aggressive abdominoperineal, approach with tissue interposition in selected patients.info:eu-repo/semantics/publishedVersio

An efficient heuristic for calculating a protected path with specified nodes

The problem of determining a path between two nodes in a network that must visit specific intermediate nodes arises in a number of contexts. For example, one might require traffic to visit nodes where it can be monitored by deep packet inspection for security reasons. In this paper a new recursive heuristic is proposed for finding the shortest loopless path, from a source node to a target node, that visits a specified set of nodes in a network. In order to provide survivability to failures along the path, the proposed heuristic is modified to ensure that the calculated path can be protected by a node-disjoint backup path. The performance of the heuristic, calculating a path with and without protection, is evaluated by comparing with an integer linear programming (ILP) formulation for each of the considered problems. The ILP solver may fail to obtain a solution in a reasonable amount of time, especially in large networks, which justifies the need for effective, computationally efficient heuristics for solving these problems. Our numerical results are also compared with previous heuristics in the literature

Cosmology with Varying Constants

The idea of possible time or space variations of the `fundamental' constants of nature, although not new, is only now beginning to be actively considered by large numbers of researchers in the particle physics, cosmology and astrophysics communities. This revival is mostly due to the claims of possible detection of such variations, in various different contexts and by several groups. Here, I present the current theoretical motivations and expectations for such variations, review the current observational status, and discuss the impact of a possible confirmation of these results in our views of cosmology and physics as a whole.Comment: 14 pages, no figures. Essay to appear in Phil. Trans. Roy. Soc. Lond. A Triennial Series (Christmas 2002 Issue

Constraining the evolution of the CMB temperature with SZ measurements from Planck data

The CMB temperature-redshift relation, T_CMB(z)=T_0(1+z), is a key prediction of the standard cosmology, but is violated in many non standard models. Constraining possible deviations to this law is an effective way to test the LambdaCDM paradigm and to search for hints of new physics. We have determined T_CMB(z), with a precision up to 3%, for a subsample (104 clusters) of the Planck SZ cluster catalog, at redshift in the range 0.01-- 0.94, using measurements of the spectrum of the Sunyaev Zel'dovich effect obtained from Planck temperature maps at frequencies from 70 to 353 GHz. The method adopted to provide individual determinations of T_CMB(z) at cluster redshift relies on the use of SZ intensity change, Delta I_SZ(nu), at different frequencies, and on a Monte-Carlo Markov Chain approach. By applying this method to the sample of 104 clusters, we limit possible deviations of the form T_CMB(z)=T_0(1+z)^(1-beta) to be beta= 0.022 +/- 0.018, at 1 sigma uncertainty, consistent with the prediction of the standard model. Combining these measurements with previously published results we get beta=0.016+/-0.012.Comment: submitted to JCAP, 21 pages, 8 figure

Automatic grape bunch detection in vineyards based on affordable 3D phenotyping using a consumer webcam.

This work presents a methodology for 3-D phenotyping of vineyards based on images captured by a low cost high-definition webcamera. A novel software application integrated visual odometry and multiple-view stereo components to create dense and accurate three-dimensional points clouds for vines, properly transformed to millimeter scale. Geometrical and color features of the points were employed by a classification procedure that reached 93% of accuracy on detecting points belonging to grapes. Individual bunches were automatically delimited and their volumes estimated. The sum of the estimated volumes per vine presented a coefficient of correlation of R = 0.99 to the real grape weight observed in each vine after harvesting.SBIAgro 2017